Simulator "nightmare" scenarios and tricks
I've heard from pilots in the past that simulator instructors like to spring unexpected situations on them and occasionally engage in other "tricks" to test their vigilance and ability to deal with the unanticipated. What sorts of situations do they come up with, and which are the most clever and/or effective, and what sort of justification do they usually provide for whatever they do? I understand that some scenarios must be practiced in the sim by pilots at regular minimum intervals, but from what I've heard there are occasionally other "tests" that go above and beyond the strictly necessary, such as nightmarish multiple-failure scenarios and the like.
On a related note, do pilots ever engage in competitions with simulators to see who can handle some specific situation the most skillfully, in the way that professional truckers sometimes compete to see who can park or maneuver a rig with the greatest precision, etc.? Or is that too expensive/frowned upon/considered immature?